FIELD OF THE INVENTION
The present invention relates to an indicating exposure meter for a camera, and more particularly to an exposure meter utilizing indicating lamps or other discrete visual indicating elements.
Exposure meters used in cameras conventionally utilize a small galvanometer for indicating whether the factors controlling a camera are set to provide film exposure. Because the indication provided by a galvanometer is in the form of a scale reading, precise information is available to a user on which direction and by how much the exposure controls of the camera must be changed to obtain a proper exposure.
The primary disadvantage of this type of exposure meter is its susceptibility to damage due to the delicate and fragile nature of a galvanometer-based exposure meter. More rugged exposure meters are known in which indicating lamps are used instead of a galvanometer. However, these exposure meters provide far less information than the galvanometer type.
It is an object of the present invention to provide a new and improved indicating exposure meter wherein the above described deficiencies are eliminated or substantially overcome.
According to the present invention, there is provided an indicating exposure meter for a camera having adjustable means positionable to set the exposure factors of the camera comprising: an array of indicating elements, each having an inactive and an active state ascertainable by visual inspection; a light measuring circuit including an element having a parameter responsive to light from a scene being photographed; a variable element having a parameter whose value is responsive to the position of said adjustable means; signal generating means responsive to the parameters of the elements for generating a signal whose magnitude is a measure of the extent of photometric imbalance resulting from the current position of the adjustable means; and comparison means responsive to the signal for controlling the state of each of the indicating elements in accordance with the magnitude of the signal so that the magnitude of photometric imbalance is ascertainable from visual inspection of the location of the active indicating elements in the array.
The signalgenerated by the signal generating means is also a measure of the displacement of the current position of the adjustable means from the position at which photometric balance would result. In response to a change in the position of the adjustable means, the comparison means causes the state of the indicating elements to indicate whether such change is in the direction toward the position at which photometric balance would result. Thus, the state of the indicating elements provides a quantitative as well as a qualitative indication of photometric imbalance.